Density Functional Theory Study on the Decay of Fullerenyl Radicals RC60鈥?/sup>, ROC60鈥?/sup>, and ROOC60鈥?/sup> (R = tert-Butyl and Cumyl) and P
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- 作者：Denis Sh. Sabirov ; Ralia R. Garipova ; Ramil G. Bulgakov
- 刊名：Journal of Physical Chemistry A
- 出版年：2013
- 出版时间：December 12, 2013
- 年：2013
- 卷：117
- 期：49
- 页码：13176-13183
- 全文大小：364K
- 年卷期：v.117,no.49(December 12, 2013)
- ISSN：1520-5215
文摘
Currently, there are no comparative studies on the possible routes of decay of fullerenyl radicals. Such information is required for development of new synthetic approaches to the fullerene derivatives, obtained via radical reactions, and understanding mechanisms of oxidative destruction of fullerene-containing materials. In the present work, we have performed a theoretical study on the possible reactions of the selected fullerenyl radicals, generated in the well-known experimental systems. We consider three main routes for the radical decay: formation of fullerene bisadducts via XC60鈥?/sup> + X鈥?/sup> reactions, dimerization of XC60鈥?/sup>, and their interaction with molecular oxygen. The calculated heat effects explain the experimental regularities of fullerene radical reactions (e.g., the reversibility of the dimerization and low reactivity of fullerenyls toward molecular oxygen). We have found that the heat effects are maximal for the dimerization of ROOC60鈥?/sup>, so the interaction of C60 with peroxy radicals may provide more effective synthetic routes to the single-bonded C60 dimers compared to the known ones. Moreover, the exothermicity of ROO鈥?/sup> addition to C60 is increased during the subsequent addition that allows reconsidering the reasons underlying C60 antioxidant activity. Additionally, polarizability and its nonadditivity of fullerene dimers XC60鈥揅60X have been found. Guided by the calculated polarizabilities, we assume a new bistable system 鈥渇ullerenyl 鈫?dimer鈥?for molecular machinery. Depending on the conditions, such a system can exist in two states differing by their response to external electric fields.